1. Field of the Invention
The present invention relates to spray gun assemblies for manufacturing polyurethane skin components.
2. Description of Related Art
Guns for spraying urethane are used in many different manufacturing applications, e.g. such as the manufacture of interior compartment components for automotive vehicles. These spray guns, when actuated, form a mixture of polyol and isocyanate and dispense the mixture through conventional dispensing means, such as a needle valve operated dispensing gun. In the well-known fashion, polyol and isocyanate, when combined, form a foam which rapidly cures into a flexible skin.
These previously known spray guns for urethane typically include a main body having a first port fluidly connected with a pressurized source of polyol, a second port fluidly connected with a pressurized source of isocyanate, and a third port for solvent. A first needle valve is fluidly connected in series with the first fluid port while, similarly, a second needle valve is fluidly connected in series with the second fluid port. These needle valves are movable between an open and a closed position. In their closed position, the needle valves prevent fluid flow of either the polyol or the isocyanate through the first and second ports, respectively. Conversely, when the needle valves are moved to their open positions, fluid flow of both the polyol as well as the isocyanate to the dispensing wand occurs.
These previously known guns for spraying urethane, however, have not proven wholly satisfactorily in use. One disadvantage of these previously known urethane spray guns is that, when the needle valves are moved to their open position, the polyol and isocyanate are directly fluidly connected with the dispensing wand. In some cases, inadequate intermixing of the polyol and the isocyanate results which, in turn, results in inadequate urethane foam production.